CGA P-20: Standard for the Classification of Toxic Gas Mixtures

18 Pages·1.7 MB·English

by  Compressed Gas Association

By Authority Of
THE UNITED STATES OF AMERICA
Legally Binding Document
By the Authority Vested By Part 5 of the United States Code § 552(a) and
Part 1 of the Code of Regulations § 51 the attached document has been duly
INCORPORATED BY REFERENCE and shall be considered legally
binding upon all citizens and residents of the United States of America.
HEED THIS NOTICE: Criminal penalties may apply for noncompliance.
e
Document Name:
CFR Section(s):
Standards Body:
Official Incorporator:
THE EXECUTIVE DIRECTOR
OFFICE OF THE FEDERAL REGISTER
WASHINGTON, D.C.

CGA P-20-2003
STANDARD FOR
CLASSIFICATION OF
TOXIC GAS MIXTURES
THIRD EDITION
COMPRESSED GAS ASSOCIATION, INC.
4221 Walney Road, 5th Floor
Chantilly, VA 20151
Phone: [phone]
Fax: [phone]
E-mail: [email protected]
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IN CASE OF A TRANSPORTATION EMERGENCY
INVOLVING A COMPRESSED GAS
In the UNITED STATES, ask for advice through CHEMTREC, the Chemical Transportation Emergency Cen
ter at the Chemical Manufacturers Association in Washington, DC.
48 contiguous states, Puerto Rico, Virgin Islands, Alaska, Hawaii, and if transporting Cana-
dian products into the United States (Toll Free) [phone]
District of Columbia, and foreign locations (exclusive of Canada) [phone]
For non-emergency information only, call
The Chemical Referral Center [phone]
If in the District of Columbia, or (collect) if
foreign location other than Canada [phone]
In CANADA, ask for advice through CANUTEC, Transport Dangerous Goods Directorate, Transport Canada,
Ottawa, Ontario.
In emergency, from all points within Canada,
call collect 24 hours a day [phone]
For non-emergency information only, call [phone]
CGA P-20-2003_ ______C =O""M'-'PR""E=.::S""S"'E"'D...::G;<.eA"'S'-'-A-"s""s"'O'-"C"'-IA!..!.T-",IO""N,-,-,. !!.IN~C~. ___________P AGE iii
PLEASE NOTE:
The information contained in this document was obtained from sources believed to be reliable and is based on
technical information and experience currently available from members of the Compressed Gas Association,
Inc. and others. However, the Association or its members, jointly or severally, make no guarantee of the results
and assume no liability or responsibility in connection with the information or suggestions herein contained.
Moreover, it should not be assumed that every acceptable commodity grade, test or safety procedure or
method, precaution, equipment or device is contained within, or that abnormal or unusual circumstances may
not warrant or suggest further requirements or additional procedure.
This document is subject to periodic review, and users are cautioned to obtain the latest edition. The Associa
tion invites comments and suggestions for consideration. In connection with such review, any such comments
or suggestions will be fully reviewed by the Association after giving the party, upon request, a reasonable op
portunity to be heard. Proposed changes may be submitted via the Internet at our web site, www.cqanet.com.
This document should not be confused with federal, state, provincial, or municipal specifications or regulations;
insurance requirements; or national safety codes. While the Association recommends reference to or use of
this document by government agencies and others, this document is purely voluntary and not binding unless
adopted by reference in regulations.
A listing of all publications, audiovisual programs, safety and technical bulletins, and safety posters is available
via the Internet at our website at www.cqanet.com. For more information contact CGA at Phone: [phone],
ext. 799. E-mail: [email protected].
Work Item 00-03
Specialty Gases Committee
NOTE-Technical changes from the previous edition are underlined.
THIRD EDITION: 2003
SECOND EDITON: 1995
FIRST EDITION: 1991
© 2003 The Compressed Gas Association, Inc. All rights reserved.
All materials contained in this work are protected by United States and intemational copyright laws. No part of this work may be
reproduced or transmitted in any form or by any means, electronic or mechanical including photocopying, recording, or any informa
tion storage and retrieval system without permission in writing from The Compressed Gas Association, Inc. All requests for
permission to reproduce material from this work should be directed to The Compressed Gas Association, Inc., 4221 Walney Road,
Suite 500, Chantilly VA 20151. You may not alter or remove any trademark, copyright or other notice from this work.
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Contents Page
Introduction .................................................................................................................................. . ...... 1
2 Scope and purpose. ..................................... . ....................................................................................... 1
2.1 Scope .................................. .......................................................... . .......................................... 1
2.2 Purpose .. . .................................................................................................................................... 1
3 Defin~ons ....................................... . .. ..... 1
4 Description of method for determining gas mixture toxicity .......................................................................... 2
4.1 Hazard zones of toxic gas mixtures ..................................................................................................... 2
4.2 Classification procedures for toxic gas mixtures ............................................................................... 2
4.3 Limiting concentrations for gas mixture toxicity .................................................................................. .4
5 Principles of method for determining gas mixture toxicity .............................................................................. 5
5.1 More than one toxic component ........................................................................................................ 5
5.2 Determination of appropriate hazard zone ........................................................................................ 5
6 Method for selecting labels for toxic gas mixtures .......................... . ..5
7 Sample calculations .................................................................................................................................. 6
8 References ............................ . . ..................................................................... 12
9 Additional references ............. . ...................................................................... 12
Tables
Table 1-Modified Haber factors for time normalization of LC data to 1 hour .............................................. .4
50
Table 2-Animal ranking (in order of preference) .... .... . ............................................................................ 4
Table 3-Toxic hazard zone limits ...... .... ... ...... ....... . .............................................................................. 7
Table 4-Labeling of pure products ........ . .................................................................................................... 10
Figure
Figure 1-LC selection algorithm ............................................................................................... 3
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cGAp-20--2003_ ___________~ C~O~M~P~RE~S~S~E=D~G~A=S~A=S=SO=C=I~AT~I=ON~,~IN~C~. _____________________P AGE1
1 Introduction
Pure gas toxic designations are well known. However, the gases included in this standard vary according to the
meaning of "toxic" or "poison," as defined by U.S. Department of Transportation (DOT) and Transport Canada's
(TC) Transportation of Dangerous Goods (TOG) Regulations [1, 2].1 Label requirements and hazard classes for
pure gases reflect DOT and TC requirements. Additional labels denoting more than the toxic hazard class may
be required.
Information on toxicity of gases has been obtained from a variety of sources. Specifically, LC and LC data
50 LO
were obtained from the National Institute of Occupational Safety and Health (NIOSH), Registry of Toxic Effects
of Chemical Substances (RTECS) and Sax's Dangerous Properties of Industrial Materials, Sixth Edition [3, 4].
2 Scope and purpose
2.1 Scope
This standard applies to all users, transporters, and manufacturers affected by label requirements and ad
dresses classifications for gas mixtures that contain a toxic component(s). This standard categorizes gas mix
tures by establishing a measurement criterion based on LC RAT values. The resultant criterion is the basis for
50
a method to calculate gas mixture toxicity.
2.2 Purpose
The purpose of this standard is to establish a means to classify toxic gas mixtures.
3 Definitions
For the purpose of this standard, the following definitions apply.
3.1 Immediately Dangerous to Life or Health (IDLH)
Level defined by NIOSH determined to be immediately dangerous to life or health. This term is used for the
purpose of respirator selection and represents a maximum concentration from which, in the event of respirator
failure, one could escape within 30 minutes without experiencing any escape impairing or irreversible health
effects.
3.2 Lethal Concentration Fifty (LC50)
Concentration of a substance in air, exposure to which for a specified length of time is expected to cause the
death of 50% of the entire defined experimental animal population.
NOTE-For this publication, LCso is defined by the following procedure: ten albino rats (five male and five female) are ex
posed to a test atmosphere for 1 hour and observed for 14 days. If five of the animals die within the 14-day observation pe
riod, the concentration level of the test atmosphere is the LCso. Where suitable test data is not available, an LCso value shall
be assigned. See 4.2 for the selection of this LCso value.
3.3 Lethal Concentration Low (LCLQ)
Lowest concentration of a substance in air, other than LC5o, that has been reported to have caused death in
humans or animals. The reported concentrations may be entered for periods of exposure which are less than
24 hours (acute) or greater than 24 hours (subacute and chronic).
3.4 LDso
Lethal dose to 50% of a specified population.
3.5 Mole fraction
Concentration ratio of a component in a gas mixture.
3.6 ppm
Parts per million, by volume (mole fraction) for gases.
1 References are shown by bracketed numbers and are listed in order of appearance in the reference section.
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3.7 Threshold Limit Value-Time Weighted Average (TL\t'-TWA)
Time-weighted average concentration of a substance for a normal 8-hour workday and a 40-hour workweek to
which nearly all workers may be repeatedly exposed, day after day, without adverse effect.
4 Description of method for determining gas mixture toxicity
4.1 Hazard zones of toxic gas mixtures
This publication classifies toxic gas mixtures into four hazard zones. They are defined as follows:
Hazard zone A-gases (mixtures) with an LC50 :0: 200 ppm;
Hazard zone B-gases (mixtures) with an LC50 > 200 ppm :0: 1000 ppm;
Hazard zone C-gases (mixtures) with an LC50 > 1000 ppm :0: 3000 ppm; and
Hazard zone D-gases (mixtures) with an LC50 > 3000 ppm :0: 5000 ppm.
TC TOG Regulations (2.14(c)) classify gases or gas mixtures as toxic if their LC value is less than or equal to
50
5000 ppm or if they are known to be toxic or corrosive to humans according to CGA P-20, ISO 10298, Deter
mination of toxicity of a gas or gas mixture, or other documentary evidence published in technical journals or
government publications [2, 5].
4.2 Classification procedures for toxic gas mixtures
The classification for toxicity of a gas mixture is based upon the LC of the gas mixture. The LC of a binary
50 50
(two component) mixture composed of a toxic gas in a nontoxic gas is calculated as follows:
LC of gas mixture in ppm
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molar fraction of toxic component
ppm LCso of toxic component
OR
ppm LCso of toxic component x 1000 000
=
ppm of toxic component
As indicated above, the LC of the toxic component must be known, calculated, or provisionally assigned.
50
The selection of an LC value for a pure gas shall follow the algorithm in Figure 1. The preferred measurement
50
standard is LC RAT, 1 hour. Lacking good data for precisely these parameters, LC RAT values for times
50 50
different from, but closest to, 1 hour were selected and adjusted to the 1 hour exposed limit. All data for expo
sures less than 0.5 hour were eliminated. Table 1 shows normalization factors for times other than 1 hour.
If no reliable LC data for rats were available, the next animals of choice in order, were mouse, rabbit, guinea
50
pig, cat, dog, and monkey. Table 2 ranks the animals of choice. Data for 1 hour were preferred.
If no reliable LC data were found for any animal, a search was conducted for a reliable LC value using the
50 LO
same hierarchy of animals. The same normalization factors for times other than 1 hour were used.
If no reliable LC or LC value was obtained, a value was provisionally assigned based on anyone or a com
50 LO
bination of the following:
decomposition or reaction products;
a correlation to L0 values (not inhalation);
50
CGA P-20-2003_ _____- -.:C"'-o""M~PR_'.!E=_'S""S"=E~D~G~A""S'_'_A~s~s~O~C!.CIA~T!.=IO~N!..o.-'" ,-,IN",C,,-. ___________P AGE 3
a comparison to other published hazard levels (e.g., IDLH); and
an analogy to similar products.
Any data chosen from these four were weighted according to the reliability of the data.
Based on the algorithm in Figure 1 along with normalization factors of Table 1 and the animal rankings of
Table 2, LCso values have been obtained for a number of gases. These are listed in Table 3. Limiting concen
trations for each gas in each hazard zone are as shown.
Begin
~\- ~ ~ ~-~.~-.-~ ~~ ~- ~~---
.... ...... .. ........ +----.. .. ---.... .....
LCso MUS LCso RBT LCso GPG LCso CAT LCso DOG I LCso MKY
(1 hour) (1 hour) (1 hour) (1 hour) (1 hour) (1 hour)
LC
50 1\0 Np 1\0 1\0 I 1\0
RAT
1 hour 1\0 1\0 1\0 1\0 1\0 TI\o 0
time ~timle t~ime Lti.m...e Lti.m...e time ti;"e
No adjust adjust adjust adjust adjust adjust i~just
Yes Y SYES Y S nS Y S Y S Y S Y S Y S YES Y S Y S Y,f.S Use
" .......
t J as
Yes Y SYES Yes Y!!S Y s Y S Y S Y S Y S Y S rY S Y s YfS
,.L.-C-1- No atdimjues t ~adjust a.tdim-Ljue-s- t a.td-jju~-st a.tdim-jLues-- t adj"" 0 ~ti;:t;- LC50
lO
RAT 1\0 1o 10 to to 10
1 hour I
No N 1\ 0 0 ~Jo 1\0
W
(1 hour) (1 hour) (1 hOUr! (1 hour) (1 hour) (1 hour)
LCLO MUS LCLO RBT LCLa GPG LeLa CAT LCw DOG LC a MKY
~~ ..~ --..- -.......- --.... ~~ ...... ~--...~ Co~rre~lat..i. o ~n to _ ...........
LDso values
Analogy
to similar
Provisionalfy
product
~ Comparison to assigned
other published value
hazard levels
".
L~ Reaction or
decomposition
product in air
Figure 1-LCso selection algorithm
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Table 1-Modified Haber factors for time normalization of LCso data to 1 hour
Time (hours) Multiply by
0.5 0.707
1.0 1.000
1.5 1.225
2.0 1.414
3.0 1.732
4.0 2.000
5.0 2.236
6.0 2.449
7.0 2.646
8.0 2.828
Table 2-Animal ranking (in order of preference)
RAT ......... rat
MUS ................................ mouse
RBT ..................... . . .... rabbit
GPG ..... . ......................... guinea pig
CAT ............................................... cat
DOG ............................................ dog
MKY .... . ............................ monkey
4.3 Limiting concentrations for gas mixture toxicity
The limiting concentrations for each gas mixture shown in Table 3 were calculated as follows:
LC of pure gas in ppm lowest molar fraction of a toxic component in a gas mixture that places the
50
mixture in Hazard zone A (x 100 for %)
LC 200 ppm
50
LC of pure gas in ppm lowest molar fraction of a toxic component in a gas mixture that places the
50
mixture in Hazard zone B (x 100 for %)
LC 1000 ppm
50
LC of pure gas in ppm lowest molar fraction of a toxic component in a gas mixture that places the
50
mixture in Hazard zone C (x 100 for %)
LC 3000 ppm
50
LC of pure gas in ppm lowest molar fraction of a toxic component in a gas mixture that places the
50
mixture in Hazard zone D ( x 100 for %)
LC 5000 ppm
50